ES2885068T3 - Force sensor for an electrophysiology catheter - Google Patents

Abstract

A force sensor (200) for measuring the magnitude of a contact force exerted by a surface of a wall of a vessel or an organ on a distal portion of a catheter, the force sensor (200) comprising an elastic tube (210 , 310, 410, 510) and at least one strain gauge (220, 430), the elastic tube (210, 310, 410, 510) having a hollow part formed in a wall thereof, not overlapping the strain gauge (220, 430) with the hollow part, wherein the hollow part comprises at least a first arcuate through slot (231), each first through slot (231) having opposite ends between which a strain gauge (220, 430) is arranged or are a plurality of strain gauges (220, 430) arranged in juxtaposition.

Description

DESCRIPTION

Force sensor for an electrophysiology catheter

technical field

The present invention relates to the field of medical devices and, in particular, to a force sensor for an electrophysiology catheter.

Background

In recent years, catheter systems have been developed for the interventional treatment of, for example, cardiac arrhythmias and refractory hypertension. For example, in the treatment of atrial fibrillation, a type of cardiac arrhythmia, an ablation or mapping catheter may be inserted into the heart through a vein or artery to find a trigger or aberrant electrical signal pathway by endocardial mapping, and then applying energy to the trigger or pathway to remove it or alter undesirable electrical signals, thus achieving healing results. Another example is the treatment of refractory hypertension by renal artery ablation, in which an ablation catheter may be arterially inserted into an artery connecting the abdominal aorta and kidney to ablate and block the pathway of the parasympathetic nerve to reduce blood pressure. blood pressure.

For ablation therapy, it is considered very important how strongly an electrode disposed at a distal end of the used catheter contacts the target vessel wall or tissue. A weak contact will lead to a superficial injury unable to allow effective blockade of aberrant electrical signals or nerve conduction. However, excessively strong contact can probably lead to tissue perforation, which increases the safety risk. To avoid these problems, existing catheters of this type are provided at the distal end with force sensors to effectively measure the contact force between the electrode and the vessel wall or tissue. For example, magnetic position sensors may be fitted to such a catheter to detect the contact force between the distal end thereof and the target organ. However, such sensors suffer from certain limitations in practical use, such as the tendency to give distorted results due to the interference of external magnetic fields and the limitation of other functionalities of the catheter such as three-dimensional magnetic positioning due to the use of magnetic fields. There are also catheter systems that use force sensitive materials as force sensors to detect loads on the distal end. Although such systems are good at measuring axial loads, they lack accuracy in measuring non-axial loads. There are more catheters that employ fiber optic systems to sense the forces of contact with the vessel wall or organ, but they are difficult to package and manufacture, are expensive, and require external electrical signal devices.

WO 2013/071361 A1 discloses an optical detection device comprising a plurality of optical light guide parts. WO 2012/142588 A1 discloses an ablation catheter system configured with a compact force sensor at a distal end for sensing contact forces exerted on an end effector. EP 2 172 240 A1 discloses a force sensing catheter for diagnosing or treating vessels within a body or body space. EP 2338430 A1 discloses a medical probe, including a flexible insertion tube, having a distal end for insertion into a body cavity of a patient and configured to contact tissue in the body cavity.

In view of the limitations described above in the practical application of all conventional systems, it is necessary to develop a force sensing device that is capable of measuring the contact force at the distal end and suitable for mass manufacturing.

Summary of the invention

It is an object of the present invention to address the inability of conventional systems to accurately measure contact forces at a distal end of the catheter by presenting an electrophysiology catheter.

In order to achieve the above and related objectives, the present invention provides an electrophysiology catheter including a distal portion of the catheter, wherein the distal portion of the catheter is provided with a force sensor, the force sensor including a elastic tube and a strain gauge, the elastic tube having a hollow portion formed in a wall thereof, the strain gauge disposed on the outside of the hollow portion. Preferably, the hollow portion may include at least one first arcuate through slot, each first through slot having opposite ends between which is disposed a strain gauge or a plurality of strain gauges in juxtaposition.

Preferably, the hollow part may include a plurality of first through slots spaced axially apart from each other in the elastic tube and staggered from each other along a circumferential direction of the elastic tube.

Preferably, the hollow portion may include two first through slots, where one strain gauge is disposed between opposite ends of one of the first through slots, while two strain gauges are disposed juxtaposed between opposite ends of the other of the first through slots. , and where one of the first through slots has a length greater than the length of the other of the first through slots.

Preferably, the hollow portion may include more than two first through slots evenly distributed along the circumferential direction of the elastic tube, each first through slot having two opposite ends between which a strain gauge is disposed.

Preferably, a center axis of the strain gauge along an axial direction of the elastic tube may be parallel to a center axis of the elastic tube.

Preferably, the hollow portion may include at least one set of through slots, each set of through slots containing a plurality of first through slots axially aligned with one another and having two opposite ends between which a strain gauge or a plurality of strain gauges are disposed. in juxtaposition.

Preferably, a length of the strain gauge in an axial direction of the elastic tube may be greater than or equal to a width of the set of through slots in the axial direction of the elastic tube.

Preferably, the hollow portion may include a plurality of sets of through slots spaced axially apart from each other in the elastic tube and staggered from each other along a circumferential direction of the elastic tube.

Preferably, the hollow portion may include two sets of through slots, wherein one strain gauge is disposed between opposite ends of one of the sets of through slots, while two strain gauges are disposed juxtaposedly between opposite ends of the other of the sets. of through slots, and wherein one of the sets of through slots has a length greater than the length of the other of the sets of through slots.

Preferably, the hollow portion may include more than two sets of through slots evenly distributed along the circumferential direction of the elastic tube, each set of through slots having two opposite ends between which a strain gauge is disposed.

Preferably, a center axis of the strain gauge along an axial direction of the elastic tube may be parallel to a center axis of the elastic tube.

Preferably, each of the first through slots may be provided at opposite ends thereof with second through slots extending along an axial direction of the elastic tube.

Preferably, the second through slots may be sausage-shaped, oval or round.

Preferably, the hollow portion may include at least one third through-coil slot, in which the strain gauge extends in the same direction as the third through-coil slot.

Preferably, the hollow portion may include a plurality of spaced apart third through slots, one or more strain gauges being disposed between each two adjacent ones of the plurality of third through slots.

Preferably, the strain gauges may be arranged in central portions of the third through slots.

Preferably, the third through groove can be formed by spiral cutting with a pitch of 1.0-6.0 mm and a number of turns of 1-3, the third through groove having a width of 0.05-0.2 mm. .

Preferably, the hollow portion may include a plurality of fourth through slots extending in an axial direction of the elastic tube and spaced apart from each other along a circumferential direction of the elastic tube, where one or more strain gauges are arranged in juxtaposition to each other. adjacent two of the plurality of fourth through slots.

Preferably, the elastic tube can be provided with sleeves at opposite ends thereof and resumes an "I"-shaped structure.

The invention is defined in claim 1. Other aspects and preferred embodiments are defined in the dependent claims. Aspects, embodiments, and examples of the present invention that do not fall within the scope of the appended claims are not part of the invention and are provided for illustrative purposes only.

In summary, compared to the design with the strain sensors superimposed on the hollow part, arranging them on solid parts of the elastic tube in the electrophysiology catheter of the present invention allows the strain gauges to collect more accurate electrical signals and thus , improve the accuracy of the contact force measurement of the distal part of the catheter.

In particular, disposing the strain gauges between opposite ends of the first arcuate through slots in accordance with the present invention or between adjacent third spiral through slots or between adjacent fourth axially extending through slots, allows the strain gauges to pick up electrical signals from higher quality. Additionally, the through-slots in the third coil impart greater circumferential uniformity to the elastic tube, helping to pick up more accurate electrical signals.

More particularly, the second axially extending through slots disposed at the ends of the first through slots according to the present invention can further reduce the stiffness of the elastic tube, thus increasing the deformability of the elastic tube, helping to improve electrical signals. collected by the strain gauges and making the measurement results more accurate.

Furthermore, the force sensor according to the present invention is less bulky, more sensitive, is less affected by magnetic fields, is immune to temperature variations and is cost-effective. Also, in addition to the magnitude of a contact force exerted by the surface of a vessel or organ wall at the distal portion of the catheter, the plurality of strain gauges can also measure axial and lateral components of the force and also an angle of associated contact. This can provide the physician with valuable additional information based on which better surgical results can be obtained.

Brief description of the drawings

Figure 1 is a schematic illustrating cardiac ablation performed by an ablation catheter comprising a force sensor according to Embodiment 1 of the present invention.

Figure 2 is a structural schematic of a distal portion of the ablation catheter comprising a force sensor according to Embodiment 1 of the present invention.

Figure 3 schematically illustrates how strain gauges are distributed in an elastic tube according to Embodiment 1 of the present invention.

Figure 4 is a structural diagram of the elastic tube with sets of through slots according to Embodiment 1 of the present invention.

Figure 5 is a structural schematic of a distal portion of an ablation catheter including an elastic tube with three arcuate through slots according to Embodiment 2 of the present invention.

Figure 6 is a structural diagram of the elastic tube according to embodiment 2 of the present invention.

Figure 7 is a schematic cross-sectional view of the distal portion of the ablation catheter according to Embodiment 2 of the present invention.

Figure 8 is a structural diagram of an elastic tube with spiral through grooves according to Embodiment 3. Figure 9 schematically illustrates how the strain gauges are distributed in the elastic tube according to Embodiment 3.

Figure 10 is a structural diagram of an elastic tube with axial through slots according to Embodiment 4. Figure 11 is a structural diagram of a distal part of an ablation catheter according to Embodiment 4.

Fig. 12 is a diagram schematically showing a Wheatstone bridge circuit of a single strain gauge in one of the above embodiments of the present invention.

Figure 13 schematically illustrates a force generated on a distal part, according to one of the above embodiments, which comes into contact with a tissue.

Figure 14 schematically illustrates a force sensor according to one of the above embodiments, which is laterally stressed.

In these figures,

100-ablation catheter; distal part of the 110 catheter; deflectable section 120; 130 main body; control handle 140; ablation electrode 150; signal conditioning circuit board 160; hanging wire 170; data acquisition device 180; 190 microprocessor; force sensor 200; 210, 310, 410, 510 elastic tubes; 220, strain gauges 430; through slot assembly 230; 231-first through slot; 240 second through groove ; 420-third through slot; tubular body 511; 520-sleeve; 530-fourth through slot; 20-percutaneous sheath; 30-left atrium; outer-distal tube 40.

Detailed description

The present invention will be described in greater detail with reference to Figures 1 to 14 in order to make the invention more apparent and easily understood. Of course, the present invention is not limited to the following specific embodiments, and general substitutions well known to those skilled in the art are also included within the scope thereof.

Furthermore, although the present invention is described in detail with reference to the accompanying schematic figures, these figures are presented solely for the purpose of facilitating the detailed description of the embodiments and not to limit the invention in any way.

As used herein, the terms "proximal" and "distal" describe relative orientations, relative positions, and directions between elements or actions, as viewed by a physician handling the product. Without intending to be limiting, a "proximal end" typically refers to an end of the product that is close to the physician during normal operation, while a "distal end" typically refers to an end of the product that enters the patient first. "axial" and "circumferential" refer to directions along the axis and circumference of an elastic tube.

As used in the specification, and in the appended claims, the singular forms "a", "an", "the", and "the" include plural referents unless the context clearly indicates otherwise. As used in the specification, and in the appended claims, the term "or" is used in the sense that includes "and/or" unless the context clearly indicates otherwise.

Realization 1

Figure 1 is a schematic illustrating cardiac ablation performed with an ablation catheter according to Embodiment 1. Figure 2 is a structural schematic of a distal portion of the ablation catheter according to Embodiment 1.

Referring to Figures 1 and 2, ablation catheter 100 includes, sequentially connected, catheter distal portion 110, deflectable section 120, main body 130, and control handle 140. Catheter distal portion 110 is equipped with an ablation electrode 150 adapted to be brought into contact with the wall of a vessel or tissue and to apply energy thereto for ablation. However, distal portion 110 of the catheter is not limited to being equipped with ablation electrode 150, as a mapping electrode may alternatively be equipped thereon. In application, ablation catheter 100 will be inserted through percutaneous sheath 20 and inferior vena cava into left atrium 30 to ablate there.

For brevity, it is hereafter assumed that the distal portion 110 of the catheter is equipped with the ablation electrode 150. However, those skilled in the art may modify details in the following description so that it is applicable to an electrode of an ablation electrode. different kind. When the distal portion 110 of the catheter exerts a force on the vessel wall or tissue, the vessel wall or tissue on the distal portion 110 of the catheter will generate a reaction force and this will be measured in accordance with the present invention as contact force. .

In this embodiment, ablation electrode 150 is made of a metallic material such as stainless steel or a platinum-iridium alloy. Ablation electrode 150 has a porous structure. In other embodiments, it can also be pore-free. The control handle 140 can control the deflectable section 120 and cause the deflection thereof. The main body of the ablation catheter 100 is generally a polymer tube, such as a polyurethane (PU), PEBAX (nylon elastomer), or nylon tube, or a PU tube with a woven metal mesh, having a diameter that does not exceed 9F. Control handle 140 is provided with a signal conditioning circuit board 160 to amplify and filter received electrical signals. Ablation catheter 100 is connected to data acquisition devices 180 and a microprocessor 190 in a final control system via pendant cables 170. Data acquisition devices 180 are configured to collect amplified and filtered electrical signals from the ablation catheter. signal conditioning circuit board 160 and transmitting them to microprocessor 190 which processes the signals and output contact force data and contact angle data. Microprocessor 190 contains related programs or algorithms for computationally processing the amplified and filtered electrical signals and obtaining contact force data and contact angle data.

In the case shown in Figure 2, the distal portion 110 of the catheter is further provided with a force sensor 200. The force sensor 200 is capable of detecting the magnitude and orientation of the contact force created from electrode contact. ablation 150 at the distal portion 110 of the catheter with the surface of the vessel wall or tissue. When the distal portion 110 of the catheter is subjected to contact force, the electrical signals from the force sensor 200 will undergo changes, and the modified electrical signals will be received, amplified and filtered, and provided to the data acquisition devices 180 by the signal conditioning circuit board 160.

In this embodiment, force sensor 200 is attached to ablation electrode 150, and this attachment may be accomplished by bonding using an epoxy-based resin or other adhesive, or by laser welding or the like.

Force sensor 200 includes an elastic tube 210 and at least three strain gauges 220. The at least three strain gauges 220 are disposed on an outer surface of elastic tube 210 and configured to detect strains in at least three directions.

In Embodiment 1 of the present invention, the at least three strain gauges 220 are arranged on respective circumferential sections. That is, they are staggered relative to each other along the axial direction of the elastic tube 210. In addition, the at least three strain gauges 220 are also staggered relative to each other along the circumferential direction of the elastic tube 210. That is, they are circumferentially spaced apart and staggered. In this embodiment, it is preferred that the number of strain gauges 220 be three. This makes it possible not only to satisfy the practical need for contact force measurement, but also to achieve cost control and avoid the bulkiness of the catheter. The projections of the three strain gauges 220 in a plane that intersects the axis of the elastic tube 210 at right angles are preferably evenly distributed along its circumference. Figure 3 schematically illustrates a distribution of strain gauges in the elastic tube according to Embodiment 1 of the present invention. As shown in Figure 3, when projected onto a plane orthogonal to the elastic tube axis, the three strain gauges 220 are evenly distributed circumferentially (ie, their centers divide the circumference into three equal 120-degree arcs).

From the foregoing description, those skilled in the art will appreciate that, as described herein, the uniform circumferential distribution of the strain gauges 220 with respect to the elastic tube 210 also includes the uniform circumferential distribution of the parallel projections of the strain gauges. strain gauges 220 in a plane perpendicular to the axis of the elastic tube.

The following description will be made in the exemplary context of three strain gauges 220 in order to facilitate the explanation of the present invention. However, the present invention is not limited to such embodiments with three strain gauges 220, because more than three strain gauges 220 may also be included. In this case, their parallel projections on a plane perpendicular to the elastic tube axis are equally preferred for distribution. evenly along the circumference of the elastic tube 210.

Continuing to refer to Figure 2, elastic tube 210 is coupled at its distal end to ablation electrode 150. Elastic tube 210 has a length of 5.0-10.0 mm and a ratio of its diameter to that of the electrode. ablation catheter 100 ranges from 0.6 to 0.9. The elastic tube 210 is a plastic or rubber (polymer) elastic tube or a metal tube. Preferably, the metal tube is made from a shape memory metal material, such as a nickel-titanium alloy or stainless steel.

Each of the strain gauges 220 essentially consists of a strain sensitive grid and a support. The strain sensitive grid is made by etching a constantan or nichrome sheet in a grid-like pattern, and is glued to the support which is a semi-rigid polymer sheet. The polymer from which the semi-rigid support is made is polyimide (PI) or polyetheretherketone (PEEK), PEEK being preferred. The support has a thickness of 5.0 gm to 10.0 gm.

Strain gauges 220 can be common such as single bridge or half bridge strain gauges or unusual such as strain gauges or rosette strain gauges. There is no particular limitation on the type of strain gauges, and a suitable type can be selected essentially based on the structure of the elastic tube 210. The strain gauges 220 each have a resistance of 120 Q to 350 Q and a factor 2.2 gauge. In addition, in order to achieve easier fastening, each of them has a width of less than or equal to 2.0 mm, preferably 0.5-2 mm, and a length of less than or equal to 5.0 mm, preferably 0.5-2 mm. 1.0-5.0 mm Preferably, 220 strain gauges have good performance in terms of accuracy and sensitivity and are immune to temperature changes, in order to ensure good measurement results. Strain gauges 220 are attached to the outer surface of elastic tube 210. Preferably, they are attached to the outer surface of elastic tube 210 using an epoxy or acrylic based adhesive or using a hot melt adhesive or the like.

Preferably, in this embodiment, the elastic tube 210 has a hollow portion on its outer surface (i.e., slots cut through the outer surface of the elastic tube 210) that impart better elasticity to the elastic tube 210 (especially in the case of a metal tube) and increases its deformability. As such, the strain gauges 220 can detect larger strains and output electrical signals that have undergone associated changes. More preferably, in this embodiment, the strain gauges 220 are disposed on portions of the outer surface of the elastic tube 210 other than the hollow portion (ie, solid portions of the elastic tube 210, as seen more clearly in Figure 2). In other words, the strain gauges 220 do not overlap the hollow part at all. This, when compared to the arrangement with the strain gauges 220 overlapping the hollow portion, this arrangement can effectively prevent signal interference and thus collect more accurate electrical signals. As a result, the force sensor 200 of the present invention can pick up higher quality electrical signals from the strain gauges 220, allowing a more accurate measurement of the contact force acting on the distal portion 110 of the catheter.

Figure 4 is a structural diagram of the elastic tube with sets of through slots according to Embodiment 1 of the present invention. As shown in the figure, in this embodiment, the hollow part includes the sets 230 of through slots. Each of the through slot assemblies 230 includes a plurality of first through slots 231 arranged in juxtaposition axially. Each of the first through slots 231 is an arcuate slot cut in the elastic tube 210 extending along its circumference. Preferably, the length of each first through slot 231 is equal to two-thirds to four-fifths of the circumference of the elastic tube 210. In addition, one or more juxtaposed strain gauges 220 are disposed on an unslotted portion of the elastic tube between opposite ends of a corresponding one of the sets 230 of through slots (shown in detail in Figure 2). In the following description, the width of each of the through-slot assemblies 230 is defined as the total width by which the plurality of first through-slots 231 contained therein extends axially, while the length of each of the sets 230 of through slots as the length that each of the first through slots 231 extends circumferentially.

Preferably, each of the strain gauges 220 extends axially a width that is equal to or greater than the width of a corresponding one of the sets 230 of through slots. For example, the two ends of the strain gauge 220 (along the axial direction) may be aligned with the respective ends of the through-slot assembly 230 or protrude beyond the respective ends of the through-slot assembly 230 therein. address. More preferably, axially with respect to elastic tube 210, the center axes of strain gauges 220 are parallel to those of first through slots 231 and elastic tube 210.

Each of the through-slot assemblies 230 contains three to seven, preferably five first through-slots 231. According to this embodiment, the plurality of through-slot assemblies 230 are provided in the elastic tube 210. Each of the through-slot 230 contains a plurality of first through slots 231, which impart greater elasticity to the elastic tube 210 and significantly facilitate the detection of deformations by means of the strain gauges 220.

As shown in Figure 4, there is more than one set 230 of through slots. The through-slot assemblies 230 are staggered from one another axially along the elastic tube 210 and staggered from each other circumferentially with respect to the elastic tube 210 (preferably, evenly along the circumference). In each of the sets 230 of through slots, the first through slots 231 are spaced apart by a distance of 0.1-0.4 mm and each has a width of 0.05-0.2 mm. Those skilled in the art will appreciate that, as described herein, the uniform circumferential distribution of the strain gauges 220 with respect to the elastic tube 210 also includes the uniform circumferential distribution of the parallel projections of the strain gauges 220 in a plane perpendicular to the axis of the elastic tube 210. In this embodiment, the number of sets 230 of through slots is three (as shown in Figures 2 and 4), and a single one of the strain gauges 220 is disposed between the two ends of a corresponding one of the through slot assemblies 230.

In another embodiment (not shown), the number of sets 230 of through slots is two. Additionally, one strain gauge 220 is disposed between the two ends of one of the through-slot sets 230, and two strain gauges 220 are disposed between opposite ends of the other set of through-slots 230 (preferably juxtaposed circumferentially, i.e. the same circumferential section of the elastic tube). The three strain gauges 220 are uniformly distributed circumferentially with respect to the elastic tube, with their centers trisecting the circumference in three equal 120 degree arcs. For example, the length of one of the through slots 230 may be greater than that of the other set 230 of through slots. In other embodiments, there may also be more than three sets 230 of through slots. The present invention is not limited to any particular number of through slot assemblies, and a suitable number of through slot assemblies can be selected by those skilled in the art based on practical need. Realization 2

Figure 5 shows a structural schematic of a distal portion of an ablation catheter according to Embodiment 2 of the present invention, and Figure 6 is a structural schematic of an elastic tube according to Embodiment 2 of the invention. In the following description, the width of a first through groove 231 is defined as the length that the first through groove extends along the axial direction of the elastic tube, while the length of the first through groove 231 is defined as the length that the first through slot 231 extends along the circumferential direction of the elastic tube.

In this embodiment, the elastic tube 310 also has a hollow portion that includes first arcuate through slots 231. Specifically, they may be arcuate slots cut into a single circumferential section of the outer surface of the elastic tube 310. Preferably, the length of each of the first through slots 231 is two-thirds to four-fifths of the circumference of the elastic tube 310. The first through slots 231 impart greater elasticity to the elastic tube 310 and allow greater deformability thereof and the pickup of "stronger" electrical signals. In this embodiment, each of the first through slots 230 is an arcuate slot cut in the circumferential wall of the elastic tube. In other embodiments, the first through slots 231 may also each be an arcuate slot of another type, such as a partially spiral slot. The present invention is not limited in this respect.

Different from Embodiment 1, according to this embodiment, the first through slots 231 in the hollow portion are not grouped in the set(s) 230 of through slots of Embodiment 1, and the number of first through slots 231 is at Minus two. The at least two first through grooves 231 are spaced apart from each other along an axial direction of the elastic tube 310 and staggered from each other along the circumference of the elastic tube 310 (preferably evenly in the circumferential direction). Furthermore, the first through grooves 231 are spaced with a pitch of 1.0 to 2.0 mm (ie, an axial gap between adjacent through grooves) and have a width of 0.05 to 0.3 mm.

In one embodiment of the present invention, the number of first through slots 231 is the same as the number of strain gauges 220. As shown in Figures 5 through 6, the number of first through slots 231 is three, and they are spaced axially apart. with respect to the elastic tube 310. Furthermore, a single one of the strain gauges 220 is disposed on an unslotted portion of the elastic tube between opposite ends of a corresponding one of the first through slots 231. Preferably, the three strain gauges 221 are distributed uniformly circumferentially, with their centers trisecting the circumference in three equal 120-degree arcs. More preferably, the first three through slots 231 are also evenly distributed circumferentially, with their centers trisecting the circumference in three equal 120 degree arcs.

In a preferred embodiment, each of the strain gauges 220 is disposed equidistant from opposite ends of a corresponding one of the first through slots 231. That is, a center of the strain gauge 220 is spaced from opposite ends of the first through slot. 231 for equal distances.

In another embodiment of the present invention, the number of first through slots 231 is less than the number of strain gauges 220, which is not shown. Specifically, the number of the first through slots 231 is two, and the first two through slots 231 are similarly arranged in juxtaposition axially and staggered relative to each other circumferentially. Furthermore, one strain gauge 220 is disposed between opposite ends of one of the first through slots 231, and two strain gauges 220 are disposed between opposite ends of the other first through slot 231. Similarly, all three strain gauges 220 are uniformly distributed circumferentially, with their centers trisecting the circumference into three equal 120-degree arcs. In this case, the length of one of the first through slots 231 may optionally be greater than that of the other first through slot 231 so that there is sufficient space to accommodate the two strain gauges 220 between opposite ends of the first through slot 231. short 231. For example, the length of one of the first through slots 231 is greater than or equal to two thirds of the circumference of the elastic tube 310, while the length of the other first through slot 231 is less than two thirds of the circumference of the elastic tube 310.

In Embodiment 2, the strain gauges 220 are preferably disposed on the same circumferential section as the first through slots 231, in order to achieve better deformation detection.

Continuing to refer to Figure 6, second through slots 240 may be formed at opposite ends of each of the first through slots 231. Second through slots 240 may be sausage-shaped, oval, or round. As shown in Figure 6, it is preferred that the second through slots be oblong, because this shape saves space, which aids in miniaturization of the ablation catheter 100. Specifically, in the case of second oblong through slots 240, their longer sides extend axially. In the case of second oval through slots 240, their main axes extend axially. In the arrangement with the first through grooves 231 in the circumferential section of the elastic tube terminating at their circumferential ends in the second through grooves 240, preferably, along the axial direction of the elastic tube 310, the center axes of the strain gauges 220 are parallel to those of the first through grooves 231 and the elastic tube 310. With the second through grooves 240, it is possible to effectively prevent stress concentration at the ends of the first through grooves 231. In other embodiments, instead of the second through slots 240 at the ends of the first through slots 231, the first through slots 231 may be curved at their ends or partially spiral, without limitation. In a preferred embodiment, strain gauges 220 are disposed near the second through slots 240 for better strain detection.

Figure 7 is a schematic cross-sectional view of the distal portion of the ablation catheter according to Embodiment 2 of the present invention. As shown in Figure 7 (in conjunction with Figure 5), the distal portion of the elastic tube 310 is received within a distal outer tube 40. The distal outer tube 40 is a single lumen tube. flexible enough not to affect the transmission of contact forces. For this, it can be made of PU, silicone rubber or another flexible material. The elastic tube 310 is a hollow tube with an inside diameter that is large enough to allow a component, such as a saline perfusion tube, magnetic positioner, or electrode, to pass through.

It should be noted that the implementations of the first through slots 231 according to this embodiment are also applicable to Embodiment 1. For example, each of the first through slots 231 in Embodiment 1 may also be provided with second through slots 240 at its ends. circumferentially opposite ends. Furthermore, in general, elastic tube 310 is structurally similar to elastic tube 210, and elements of elastic tube 210 and elastic tube 310 denoted by the same reference numerals (for example, strain gauges 220) are generally similar in terms. of construction and operation.

Realization 3

Figure 8 is a structural diagram of an elastic tube with spiral through grooves according to Embodiment 3, and Figure 9 schematically illustrates how the strain gauges are distributed on the elastic tube according to Embodiment 3.

As shown in Figures 8 to 9, there are one or more third spiral through grooves 420 cut into the outer surface of the elastic tube 410. The number of spiral through groove(s) may be one, two or more than two. The greater the number of the third or third through slots 420, the greater the circumferential smoothness of the elastic tube 410 and the lower the elastic modulus thereof. In practice, the number of spiral through grooves can be appropriately selected in accordance with a strain measurement range of the strain gauges 430. Preferably, when three strain gauges 430 are used, three third through grooves 420 are formed, so that each of the strain gauges 430 is disposed between a corresponding two of the third through slots 420.

In the case of two or more such spiral through groove(s), they are spaced with a pitch of 1.0-6.0 mm and extend 1 to 3 turns, preferably 2 turns. In addition, each of them has a width of 0.05-0.2 mm. Also, to avoid stress concentration, both ends of each of the third through slots 420 are curved, for example semi-oval.

Continuing to refer to Figure 9, the strain gauges 430 are set consistent with the direction of the coils and are disposed at an angle to the axis of the elastic tube 410. That is, the strain gauges 430 extend in the same direction. direction than the spirals. Preferably, the strain gauges 430 are disposed in central portions of the coils. Similarly, the strain gauges 430 are evenly distributed circumferentially with respect to the elastic tube 410. In this embodiment, the centers of the three strain gauges 430 equally trisect the circumference of the elastic tube 410 in identical 120 degree arcs.

Realization 4

Figure 10 is a structural diagram of an elastic tube with axial through slots according to Embodiment 4, and Figure 11 is a structural diagram of a distal part of an ablation catheter according to Embodiment 4.

As shown in Figures 10 to 11, in this embodiment, the elastic tube 510 includes a tubular body 511 and sleeves 520 for receiving opposite end portions of the tubular body 511, making the entire structure of the elastic tube 510 thinner in the middle. and thicker at the ends, appearing in cross section as the letter "I". When a distal end of the elastic tube 510 is tightened, the tubular body 511 can easily detect a resulting deformation, improving the elasticity of the elastic tube 510.

Sleeves 520 may be a nickel-titanium alloy or stainless steel, and sleeves 520 are attached to tubular body 511 by laser welding or an adhesive. The diameter ratio of the sleeves 520 to the tubular body 511 ranges from 1.1 to 2.0, with 1.2 being preferred. One of the sleeves 520 is further glued or laser welded to the ablation electrode 150.

In particular, for example, three or more fourth through slots 530 are cut in the tubular body 511 in such a way that they are evenly distributed circumferentially with respect to the elastic tube 210. The fourth through slots 530 may be sausage-shaped slots, oval or round, or beveled rectangles, or otherwise to impart higher elasticity to the elastic tube 510 and low resistance to the elastic tube 510 while avoiding stress concentration. In the case of the fourth oblong through slots 530, each of them has an axial length of 2.0-5.0 mm and a circumferential width of 0.05-0.3 mm.

In the case shown in Fig. 10, the fourth through slots 530 are circumferentially spaced apart from each other with respect to the tubular body 511, a strain gauge 220 is disposed between each two of the adjacent fourth through slots 530. With this design, when the distal end of the elastic tube 510 is under tension, the strain gauges 220 disposed between the fourth through slots 530 can detect a resulting tensile or compressive deformation of the solid portion.

Although various preferred embodiments have been described above, the present invention is not limited to these described embodiments. For example, multiple strain gauges may be disposed in juxtaposition between each two of the adjacent fourth through slots. As another embodiment, one or more fourth sets of through slots, each containing a plurality of fourth sets of through slots, may be formed with one or more strain gauges disposed between every two adjacent ones of the fourth sets of through slots. As yet another embodiment, between each two of the adjacent third through slots, a plurality of strain gauges may be disposed, each extending in the same direction as the spiral through slots.

Although the electrophysiology catheter according to the present invention is described in detail and implemented with an ablation catheter for illustrative purposes, the present invention is not limited to this, because the electrophysiology catheter can also be, for example, an ablation catheter. mapping catheter or the like.

Figure 12 is a schematic circuit diagram of the Wheatstone bridge of one of the strain gauges detailed above in conjunction with the above embodiments. Figure 13 schematically illustrates a force generated on a distal part, according to one of the above embodiments, which comes into contact with a tissue. Figure 14 schematically illustrates a force sensor according to one of the above embodiments, which is laterally stressed. Hereinafter, although the force sensor subjected to the lateral force Fr, as shown in Figure 14, will be described as implemented as the force sensor 200 of embodiment 2 for exemplary purposes, those skilled in the art will readily appreciate that the following description is also applicable to the force sensors of the other embodiments.

Referring to Figure 13, for example, when the distal portion 110 of the catheter contacts the myocardium, the elastic tube 210 (by way of illustration, and the same applies to the following) will deform and the strain gauge 220 will deform. will stretch or compress accordingly. Specifically, when the strain gauge 220 is stretched, the strain-sensitive grid metal wire pattern therein will elongate, leading to an increase in its resistance. When the 220 strain gauge is compressed, the metal wire pattern will shorten, leading to a decrease in resistance. That is, regardless of stretching or compression, the resistance will vary. The change in resistance of strain gauge 220 is then amplified, for example by the Wheatstone bridge of Figure 12, and output as a voltage change. The Wheatstone bridge can be implemented as a single bridge or selected as a half or full bridge to facilitate signal amplification.

Referring to Figures 13 and 14, the contact force F experienced by the distal portion 110 of the catheter can be broken down into a lateral component Fr and an axial component Fn. Referring to Figure 13, based on pure bending theory, under the action of the lateral component Fr, strain gauge 220 will stretch to a positive strain value if it is above the central axis of ablation catheter 100. , it will either compress to give a negative strain value if it is located below the central axis of the ablation catheter 100, or it will remain nearly the same to give a zero strain value if it is located on the central axis. In this way, strain detection in three directions can be achieved by three strain gauges 220, and their resistance changes corresponding to lateral and axial strains can be measured and then processed by the microprocessors 190 to determine the contact force F and an associated contact angle.

In those embodiments, the strain gauges 220 are connected to respective microprocessor systems, each of which includes a corresponding one of the data acquisition device 180. The data acquisition device 180 is configured to collect electrical signals from the respective strain gauge. 220 and provide the collected electrical signals to microprocessor 190. Microprocessor 190 is configured for computational processing of electrical signals from all strain gauges 220.

Each of the microprocessor systems may further include at least one measurement device that is connected to data acquisition device 180 and microprocessor 190 and is capable of directly measuring resistance or indirectly measuring voltage or current. Each of the microprocessor systems can be powered at 1.0-10 V, preferably 1.25 V.

In summary, compared to the design with the strain gauges superimposed on the hollow part, arranging them on solid parts of the elastic tube in the electrophysiology catheter of the present invention allows the strain gauges to pick up more accurate electrical signals and thus, improve the accuracy of the contact force measurement of the distal part of the catheter.

In particular, disposing the strain gauges between opposite ends of the first arcuate through slots, in accordance with the present invention, or between adjacent third spiral through slots or between adjacent fourth axially extending through slots allows the strain gauges to pick up a signal. higher quality electrical In addition, the through slots in the third coil impart greater circumferential uniformity to the elastic tube, helping to pick up more accurate electrical signals.

More particularly, the second axially extending through slots disposed at the ends of the first through slots according to the present invention can further reduce the stiffness of the elastic tube, thus increasing the deformability of the elastic tube, helping to improve electrical signals. collected by the strain gauges and making the measurement results more accurate.

Furthermore, the force sensor according to the present invention is less bulky, more sensitive, less affected by magnetic fields, immune to temperature variations, and cost effective. Also, in addition to the magnitude of a contact force exerted by the surface of a vessel wall or an organ at the distal portion of the catheter, the plurality of strain gauges can also measure axial and lateral components of the force and also an angle associated contact. This can provide the physician with valuable additional information based on which better surgical results can be obtained.

The description presented above is merely that of some preferred embodiments and does not limit the scope thereof in any way. Any and all changes and modifications made by those skilled in the art based on the above teachings fall within the scope.

Claims (11)

Claim 1. A force sensor (200) for measuring the magnitude of a contact force exerted by a surface of a vessel wall or an organ at a distal portion of a catheter, the force sensor (200) comprising an elastic tube (210, 310, 410, 510) and at least one strain gauge (220, 430), the elastic tube (210, 310, 410, 510) having a hollow part formed in a wall thereof, not overlapping the strain gauge ( 220, 430) with the hollow part, in which The hollow portion comprises at least one first arcuate through slot (231), each first through slot (231) having opposite ends between which a strain gauge (220, 430) or a plurality of strain gauges (220, 430) are arranged. ) in juxtaposition. 2. The force sensor (200) according to claim 1, wherein the hollow part comprises a plurality of first through slots (231) spaced axially apart from each other in the elastic tube (210, 310, 410, 510) and staggered between yes along a circumferential direction of the elastic tube (210, 310, 410, 510), and preferably, a central axis of the strain gauge (220, 430) along an axial direction of the elastic tube (210, 310 , 410, 510) is parallel to a central axis of the elastic tube (210, 310, 410, 510). 3. The force sensor (200) according to claim 2, wherein there is more than one strain gauge, the hollow part comprises two first through slots (231), where one of the strain gauges (220, 430) is arranged between opposite ends of one of the first through slots (231), while two of the strain gauges (220, 430) are disposed in juxtaposition between opposite ends of the other of the first through slots (231), and where one of the first through slots (231) has a length greater than the length of the other of the first through slots (231) along the circumferential direction of the elastic tube (210, 310, 410, 510). The force sensor (200) according to claim 2, wherein there is more than one strain gauge, the hollow part comprises more than two first through slots (231) evenly distributed along the circumferential direction of the elastic tube ( 210, 310, 410, 510), each first through slot (231) having two opposite ends between which at least one strain gauge (220, 430) of the strain gauges is disposed. The force sensor (200) according to claim 1, wherein the hollow portion comprises at least one set of through slots (230), each set of through slots (230) containing a plurality of first through slots (231) axially aligned with each other and having two opposite ends between which a strain gauge (220, 430) is disposed or a plurality of strain gauges (220, 430) are disposed in juxtaposition. 6. The force sensor (200) according to claim 5, wherein the length of the strain gauge (220, 430) in an axial direction of the elastic tube (210, 310, 410, 510) is greater than or equal to the width of the set of through slots (230) in the axial direction of the elastic tube (210, 310, 410, 510). The force sensor (200) according to claim 5, wherein the hollow portion comprises a plurality of sets of through slots spaced axially apart from one another in the elastic tube (210, 310, 410, 510) and staggered from one another at along a circumferential direction of the elastic tube (210, 310, 410, 510), and preferably, a central axis of the strain gauge (220, 430) along an axial direction of the elastic tube is parallel to a central axis of the elastic tube (210, 310, 410, 510). The force sensor (200) according to claim 7, wherein there is more than one strain gauge, the hollow portion comprises two sets (230) of through slots, wherein one of the strain gauges (220, 430) is disposed between opposite ends of one of the through-slot assemblies (230), while two strain gauges (220, 430) of the strain gauges are disposed juxtaposed between opposite ends of the other of the through-slot assemblies (230), and wherein one of the through-slot sets (230) has a length greater than the length of the other of the through-slot sets (230) along a circumferential direction of the elastic tube (210, 310, 410, 510). ). The force sensor (200) according to claim 7, wherein there is more than one strain gauge, the hollow part comprises more than two sets (230) of through slots evenly distributed along the circumferential direction of the elastic tube (210, 310, 410, 510), each set of through slots (230) having two opposite ends between which at least one of the strain gauges (220, 430) is disposed. The force sensor (200) according to any one of claims 1 to 9, wherein each of the first through slots (231) is provided at opposite ends thereof with second through slots (240) extending along an axial direction of the elastic tube (210, 310, 410, 510), and preferably the second through slot (240) is sausage-shaped, oval or round. An electrophysiology catheter, comprising a distal catheter portion, wherein the distal catheter portion is provided with a force sensor (200) according to any one of claims 1 to 10.